FIG. 5 shows a typical conventional heat exchanger which requires the heat exchange between a heat medium (for example, a cooling medium (refrigerant) or a brine) flowing in the heat exchanger and air passing through the heat exchanger. A heat exchanger, as shown in FIG. 5, is comprised of a pair of header pipes 1 extending in parallel relation to each other, a plurality of tubes 2 disposed between the header pipes and connected to the header pipes at their end portions, a plurality of radiation fins 3 provided on the sides of the tubes, a pair of reinforcement members 4 disposed on the top and bottom radiation fins, and brackets (not shown) for supporting the heat exchanger which are attached to the upper and lower portions of each header pipe.
Each header pipe 1 is constructed from a straight pipe having a circular cross section. A plurality of connection holes 11 are formed on the periphery of the header pipe with a predetermined pitch in the axial direction of the header pipe. The end portion of each tube 2 is inserted into a corresponding connection hole 11. Both ends of each straight pipe are closed by caps 1a. An inlet tube 1b for introducing the heat medium into the heat exchanger is connected to one of the header pipes 1, and an outlet tube 1c for delivering the heat medium out from the heat exchanger is connected to the other header pipe.
Tube 2 is formed as a straight tube which is flattened in the horizontal direction. The end portion of tube 2 is inserted into connection hole 11 of header pipe 1, and fixed therein by, for example, brazing. Corrugated type radiation fins 3 are fixed on the upper and lower surfaces of each tube 2 by, for example, brazing.
In the above construction of the heat exchanger, it is necessary to use four caps to close the open ends of header pipes 1 thereby adding to the number of parts of the heat exchanger.
In addition, the heat exchanger has to be preassembled before the heat exchanger is introduced into a furnace for brazing. Accordingly, it is necessary to use several jigs to fix tubes 2 and reinforcement members 4 to header pipes 1 in the preassembly of the heat exchanger, thereby complicating the process of assembling the heat exchanger.
Furthermore, reinforcement member 4 disposed on the surface of radiation fin 2 cannot be securely connected to header pipes 11 since the outer peripheral surface of header pipe 11 is curved. This arrangement thus fails to provide adequate overall strength of the heat exchanger.